Synthesis
Step 2: Synthesis of (4-chlorophenyl)(piperazin-1-yl)methanone (C)
Dissolve tert-butyl 4-(4-chlorobenzoyl)piperazine-1-carboxylate (26 g) in dichloromethane (350 mL). To the solution was added 4 M hydrochloric acid/dioxane solution (150 mL). The reaction mixture was stirred at room temperature for 4 hours, during which time the formation of a white precipitate was observed. Upon completion of the reaction, the mixture was concentrated to remove the solvent. The resulting white solid was washed with ether. Subsequently, the white solid was treated with 1 N sodium hydroxide solution (200 mL) and extracted with ethyl acetate (3 x 100 mL). The organic phases were combined, dried over anhydrous sodium sulfate and concentrated to give the target product (4-chlorophenyl)(piperazin-1-yl)methanone (17.79 g, 99% yield).
Product characterization data: 1H-NMR (hydrochloride, 300 MHz, MeOD): δ 2.80-2.90 (m, 4H), 3.20-3.80 (m, 4H), 7.29-7.36 (m, 4H).
References
[1] Patent: WO2006/71875, 2006, A1. Location in patent: Page/Page column 78
[2] Bioorganic and Medicinal Chemistry, 2012, vol. 20, # 2, p. 1139 - 1148
[3] Bioorganic and Medicinal Chemistry Letters, 2014, vol. 24, # 16, p. 3739 - 3743
[4] Archiv der Pharmazie, 2017, vol. 350, # 8,
[5] Patent: CN107226807, 2017, A. Location in patent: Paragraph 0546-0548
